As a system for loading a disc cartridge case in a disc playback device, one as shown in FIGS. 1-4 has been proposed. The disc playback device shown in these figures is of a type which comprises a disc cartridge case A and a main body B and in which a disc 1 housed in the case A is loaded with the case A in the main body B for playback thereof.
The case A is of a rectangular shape in its plan view as shown in FIGS. 1 and 2 and consists of a hollow plate-like member having a certain thickness and being capable of housing the disc 1 therein in a state in which the disc 1 can be played back. The case A is formed in its one side portion 2a with a groove 5 which extends from an end surface 3 from which the case A is inserted into the main body B to a point in the vicinity of an end surface 4 from which the case A is not normally inserted. The case A is formed also in its other side portion 2b with a groove 6 extending over a length l from the end surface 3. The insertion end surface 3 and the non-insertion end surface 4 are flat surfaces crossing at right angles with the side surfaces 2a and 2b.
The main body B plays back the disc 1 with the case A housing the disc 1 being loaded in a predetermined position therein. As shown in FIGS. 3 and 4, a turntable 8 rotated by a disc drive motor (not shown) is provided above a chassis 7 of the main body B. Above the turntable 8 is provided a vertically movable disc cartridge case holder 9. Gide walls 10 and 11 are formed on the upper surface of the holder 9 for guiding the case A. A stop 12 is formed on the inner surface of the guide wall 10 for preventing an erroneous insertion of the case A.
For loading the case A in the main body B in the above described disc playback device, the case A is inserted from the insertion end surface 3 into the holder 9 in its uplifted position in the direction of arrow P1, with the upper surface of the case A facing upwardly. When the center of the case A has reached a point above the turntable 8, the holder 9 is lowered and thereby permits the turnable 8 to relatively enter the inside of the case A through a turntable insertion opening (not shown). Thus, when the holder 9 has reached its lowermost position, the disc 1 is placed on the turntable 8.
In the case where the case A is inserted in the holder 9 in a correct insertion posture as described above, the stop 12 is located in the groove 5 as shown in FIG. 4 thereby permitting the case A to be inserted in the direction of arrow P1.
In this disc playback device, if it is attempted to insert the case A into the holder 9 in a posture which is not normal, the stop 12 abuts against a portion of the case A other than the groove 5 and thereby prevents the case A from being inserted to the predetermined position. If, for example, it is attempted to insert the case A from the insertion end surface 3 into the holder 9 with its lower surface facing upwardly, the stop 12 abuts against a wall portion 13 which closes the end portion of the groove 6 when the stop 12 has moved in a relative movement in the groove 6 by the distance l so that the case A cannot move further in the direction of arrow P1. If, again, it is attempted to insert the case A from the non-insertion end surface 4 into the holder 9 with its upper surface or lower surface facing upwardly, the left or right side end portion of the non-insertion end surface 4 abuts against the stop 12 and in this case also the case A cannot move further in the direction of arrow P1. In this manner, the proposed device can prevent erroneous insertion of the case A into the holder 9.
In the device for preventing erroneous insertion of the disc cartridge case, the stop 12 can be provided at only one location on one guide wall 10. This arrangement has the disadvantage that, if the case A is forced into the holder 9 in an incorrect insertion posture, there is likelihood that the stop 12 is not strong enough to block the advancing case A so that the case A pushes the stop 12 aside and moves in the direction of arrow P1 causing damage to the case A or the main body B.
The structure of the proposed device in which the grooves 5 and 6 are formed in the side portions of the case A complicates the design of the case A and, moreover, necessitates wall portions for forming the grooves 5 and 6 in the case A with resulting difficulty in making the case A in a compact design.